They were on sale, and to my pleasant surprise, I discovered I had a leftover frequent-buyer credit at the little independent bookstore at the edge of campus. (The new Wagamama cookbook is much better than the old one, incidentally.)
I hadn't intended to buy books but was frantically trying to deal with the fact that I've lost my copy of Persecution and the Art of Writing, which I was teaching today, and all three library copies were checked out (probably by my three students). The Penn Book Center didn't have it, though, nor did the official Penn bookstore — and yes, I'd looked locally in NY over the weekend. It's an oddly difficult book to acquire; so I ended up buying the Kindle edition from Amazon (shudder), downloading it, taking screenshots, making myself a PDF from those and printing it out.
I'm not a luddite. I just hate reading on-screen.